Many theorists, decision-makers, and policy-makers may have harbored this question for months that what features Trump's foreign policy will have. This question is becoming especially vital, as Trump has been elected as the US president. It is really difficult to answer this question. Even the great theorists of international relations appear to have failed to answer the question in a more reliable way. For example, the most prominent theorist of offensive realism, John Mearsheimerhas said: “There are similarities between our and Trump’s views, but he denigrates our views.” The difficulty to answer has several reasons. One is that Trump has no political background. Second, the inconsistencies in his campaign rhetoric on foreign policy are evident as those in his domestic policy. For example, in domestic policies, he advocates the increase in the administration budget and spending that in the US infrastructure on one hand, and is paradoxically a supporter of rich tax cuts for on the other. The contradiction can clearly be seen here. How is it possible to increase the administration budget and at the same time reduce the tax rates (up to 19 percent, including those paid by financiers and billionaires)? A replica of this contradiction is evident in his foreign policy. On one hand, it is said in all his slogans that the US should not be involved overseas, and on the other, he said in his slogans that he would increase the US defense budget, which is another evident paradox. Normally and reasonably, increased defense budget is associated with interventionism. So one of the reasons why the logic behind his foreign policy cannot be correctly guessed stems from such contradictions.

Despite the complexity and ambiguity, with regard to his campaign promises and also with regard to the structural constraints of the international structure and the specific structure of areas as well as the power structure in the US (especially the role of Congress and public opinion) and also with regard to his being elected by the people who voted for him- and the fact that they voted for his slogans and promises- the logic behind his foreign policy can be somewhat recognized, though with a degree of possibility (not with a high possibility, but with a nearly 70% possibility).

America's foreign policy logic in Trump’s term of office will probably not be “thick liberal” interventionism. It was Ms. Clinton whose records and campaign rhetoric denoted liberal interventionism. Contrary to what many would expect, Republicans are not principally too interventionist. On the contrary, Democrats (due to the emphasis on the relationship between domestic issues and foreign policy, peace, human rights, weapons of mass destruction, etc.) are in fact more interventionist than Republicans. Trump might almost follow the traditional equation of Republicans. America entered World War I andIIat the time when Democrats were in charge of Administration.

It may be said that America faced the two World Wars I and II as a fait accompli, and even if the Republicans had been in charge of Administration, they would have been involved. However, America entered the Korean War(Truman era) and undertook the huge and costly Vietnam War (Kennedy era) both in the Administration of Democrats. Both Wars (Korean War with the advent of Eisenhower and the Vietnam War with Nixon’s coming to power) have ended in the Republicans periods.

Trump's foreign policy is more likely to be similar to America's foreign policy in the 19th century than that in the aftermath of the Second World War or after 9/11. In fact, the logic of America's foreign policy (inspired by the book “Logic of America's Foreign Policy” (written by Patrick Callahan) would be likely to be isolationistic; not like the isolationism of the nineteenth century, but a type that can be called "new isolationism", as suggested by Trump campaign rhetoric.

Isolationists’ pivotal argument is that America does not have to be the world’s leader because being so entailed expenses. The hegemonic role as a leader is costly for America.Why should America spend money in Europe? Why should it spend for its allies in the Persian Gulf? These costs should be expended domestically. Isolationism results in neutrality, autonomy, deterring rivals and enemies from the security geography of America, continentalism (keeping a distance from Asia and Europe), unilateralism, protectionism and erecting walls around America, protection of the Constitution of the US, and forming case coalitions against the enemies who threaten America's vital interests. Many of these points can be somehow found in Trump’s campaign promises. Shouldn’t we consider the emphasis on domestic issues of America, staying away from European and Asian allies, deporting Mexican immigrants and erecting a wall around America, staying away from the Persian Gulf allies, anti-Iranian and anti-ISIS attitudes (possibly as threats to vital interests of America), and characterizing America's institutions and political system as corrupt as the signs of isolationist ideas.

Why new isolationism? However, the US had not yet entered the global scene before the end of 19th century, but after the Second World War, they have become heavily involved in the global scene. So their isolationism cannot be a replica of that of the 19th century. In particular, thepower structurein the US will not allow them to demonstrate exactly the pure isolationism of 19th century. So, America may be an isolationist to a large extent, but global and regional conditions, the power structure in America, new threats and international pressure (including pressure from America’s European and Asian allies) may occasionally prohibit America from being isolationist. Taking this into account, America's foreign policy may be a mixture of foreign policies of Bill Clinton and George W. Bush. But global conditions (such as 9/11 that made President George W. Bush undergo interventionism in foreign policy) may make Trump become an interventionist in foreign policy against his promises, but in normal and stable conditions, he may resort to isolationism.

This foreign policy with such features brings about challenges for America’s European and Asian allies. A result of such a foreign policy may be the return of realism to Europe and some other world regions such as the Middle East. It would be difficult for America’s European and Middle Eastern allies to lose the support they had for decades been accustomed to.

They will either repress America to come back to the world stage or may adopt the increasingly realistic self-help approach if America is reluctant. It can be said that isolationism is the another side of realism (thin realism) coin. But on the other hand, the more isolationist America is, the more America’s European and Asian allies will move toward thick realism. In fact, the inclination to thick realism may be the logical reaction to America's new isolationism. Of course, Global pressures and the structure of power in America may make them fluctuate between realism and isolationism and send signals of confusion and turmoil in foreign policy to allies, rivals, and enemies. The world’s realistic nature and the potential confusion of America are something that would be dangerous for the world today.

This foreign policy is what probably desirable for America's enemies and rivals and unpleasant for America's friends and allies. But the new isolationism (and not the isolationism) has the following remarkable features: They will recognize the crucial areas of influence of Russia (this aspect will be very similar to the realist idea) and will try to look at Russia not as an enemy but as a rival. They will avoid approaching regions critical for Russia, such as Ukraine and the "near abroad" of Russia like Georgia. This foreign policy will create a breathing space for Russia and America's European friends will adopt a self-help policy, because they will feel that America has betrayed them and has left them alone against the threat of the Russian bear. Especially Britain, backed by its allies, will try to harness Russia without the support of America, and strengthen its defense and military power. Fear of Russian threat will ingurgitate the European geographical space. What would then happen to newly formed European states, such as Poland, Czech Republic, Slovakia, Lithuania, Latvia, and Estonia? They will either become close toOld Europe or take refuge with the Russia to be secure of its danger, because, in the realistic point of view, the enemy’s threat may be so heavy that the enemies decide to come close their enemies; that is taking refuge with the enemy to be secure against it. This will be something like what happened in the 1930s. But the new feature of isolationism (which is different from isolationism) will probably be that on the contrary with Russia, they will express more opposition against China. Why? The reason is that China is the only global competitor that may be replaced for America in the following decades. In this policy, on the contrary with the policy of involvement with Russia, a policy of confrontation with and containment of China will be put on top of the agenda of America. Challenges with China may increase and China may demonstrate an increasingly realistic foreign policy.

Conflicts might escalate between America and China over the issue of Taiwan and the South China Sea, and the tension may rage. Is this just the incidence that has preoccupied theorists of international relations for years? Some, including realists, have predicted for decades that the war between China and America will be inevitable. Is Trump's foreign policy will set the stage for such a war? We should wait and see what will happen in practice.

Realism could be further strengthened in the Persian Gulf region. America's former allies will find themselves lonely against threats facing them. They will strengthen their self-reliance and if self-help policy fails, they may become close to Russia and China. If America relinquishes the Persian Gulf compared to the past, China (however reluctantly) will try to establish security in the region. The reason for the probable reluctance of China is that China’s dependence on the region’s energy cannot be compared to that of the US, particularly at the time when the US have not only reached self-sufficiency in energy, but they have managed to export energy, and may not let Chine take a free riding (Providing regional security and spending exorbitant costs and China's use of the region's energy). One of the requirements of the isolationist foreign policy is that America will intervene only when its vital interests are at stake. It seems that in Trump’s conception of these vital interests and in his understanding of threats, apart from China (that threatens America's vital interests in the world), Iran and ISIL threatens America's vital interests (at least at the regional level). Although in my opinion, the Islamic Republic of Iran is not threatening America's vital interests, but due to the hostile atmosphere and the cut-off between Iran and America, Trump, more than his predecessors, regards Iran as a threat to their vital interests. America will seek to form case alliances against Iran and ISIL, but the weakness of this policy will be that just as the US does not let their European and Middle Eastern allies have a free riding, the regional and European allies will be reluctant to let the US have a free riding (through case coalition building by America), because when America’s allies are offended by America’s isolationism it is natural that they hardly support the case coalition building policy of America (for example against the Islamic Republic of Iran).

But the policy of coalition-building against ISIL will work because ISIL is regarded as a global threat. However, despite Trump's weakness in forming a coalition against the Islamic Republic of Iran, Iran's biggest perceived risk stems from his unpredictability and strong opposition to Iran. JCPOA may face many challenges. The JCPOA, challenged in Obama’s term of office, will face challenges and difficulties several times during this period. Although it is unlikely that Trump will break the deal, considering the reflection of America’s threats, sayings, and rhetoric in Iran and the reactions of the Iranian decision-makers, especially at the highest level of decision-making, Rouhani’s government will face more difficulty than ever before. Hence there is a risk of confrontation with Iran. On the other hand, a strategic mistake may occur between Iran and America amid the signals of threats to Iran. In particular, in the Persian Gulf region where the Iranian and US navy traffic near each other, any strategic error may exacerbate the conflict.